问题
选择题
The old couple walked rather slowly, and could be seen, from time to time, to stop and rest, ________ out to sea.
A．to be staring
B．stared
C．having stared
D．staring
答案
答案：D
D 考察非谓语动词，stare的逻辑主语是the old couple，所以选择D，staring选择副词短语，在句中做伴随状语。